DATA COMPRESSION APPARATUS AND METHOD FOR ENCODING AND DECODING MULTI- LINE SIGNALS

Apparatus and method for encoding and decoding a signal which is divided into a plurality of signal lines, each of which is a successive line of pixel signal values taken from a two-dimensional informational field. The apparatus for encoding includes the following elements: means for deriving a neighborhood value representing the pixel signal values taken from the two-dimensional field in the neighborhood of a pixel signal value to be encoded, which neighborhood value is based, at least in part, on a pixel signal value in another signal line than that in which the pixel signal value to be encoded is located: means for deriving the difference between the neighborhood value and the pixel signal value to be encoded; and means for outputting the difference as the encoded representation of the pixel signal value to be encoded. In an alternative embodiment of the apparatus for encoding, the means for deriving a neighborhood value bases the neighborhood value on an average of at least two of the signal values from the neighborhood of the pixel signal value to be encoded.